Studies on the regulation of glycogen synthase phosphorylation in vitro and in vivo will be continued. Glycogen synthase will be purified from muscle of control and hormone-treated rabbits. The purified enzyme will be characterized in terms of phosphate content and kinetic properties. The physiological role of phosphorylase kinase in catalyzing glycogen synthase phosphorylation will be investigated using the "I-strain" of mouse. A cAMP-independent glycogen synthase kinase will be purified from rabbit liver and characterized in terms of physical and enzymatic properties.